Process for producing anhydrous aluminum chloride



Patented July 12, 1932 UNITED STATES PATENT OFFICE m1. arm, or nr'rrEnrnLn, GERMANY, assrenoa no I. e. r'annnmnusrnm AKTIENGESELLSCHAFT, or rnenxronr-on-rnn-mm, GERMANY, a conrona'rrou OF GERMANY rnocnss non rnonucme aumnous anummum cnnonrnn Ho Drawing. Application filed January 28, 1929, Serial No. 835,746, and in Germany February 7, 1928.

This invention relates to the manufacture of anhydrous aluminum chloride. It is well known that when chlorine is made to act upon raw materials such as clay, kaolin, bauxite I etc. containing both alumina and silica in the presence of a reducing agent, such as carbon or carbon monoxide, the silica (besides other constituents such as iron oxide, titanium oxide etc.) is converted into chloride together 10 with the alumina.

' The production of silicon tetrachloride along with aluminum chloride in this manner is, for example, the object of the United States Patent 1,238,604. In other cases,

1 however, when there is no possibility of utilizing the resulting silicon tetrachloride, the formation of this product, the amount of which often runs up closely to that of the aluminum chloride, only results in a corre- 50 sponding loss of chlorine. When aluminum chlorideisto be produced by this method on an industrial scale, for example for purposes connected with the petroleum industry,

om silic'ious material containin alumina,

its manufacture must be indepen ent of the questionable chance of sale of the silicon tetrachloride simultaneously formed, and any considerable loss of chlorine must be avoided.

My experiments have shown that the for- 80 mation of aluminum chloride does not only occur when bringing alumina into contact with chlorine in the presence of reducing materials take place when silicon chloride is admixed to the chlorine and the chlorination is carried out at temperatures above 500 0., according to the equation I have found that when using a mixture '50 percent, has the efiect of converting part for instance, carbon, but may also.

of about equal parts of SiCl, and chlorine and carrying out the reaction at about 750 C.,'there is no surplus formation of SiCh, due to reaction with the said materials, the entire chlorine content of the gas mixture being utilized for the formation of aluminum chloride.

The effect of the presence of silicon chloride in the .chlorine seems to. be due to the shifting of the equilibrium of the reaction towards the exclusive formation of aluminum chloride. This is enhanced by the observation that the presence of silicon chloride in the chlorine gas, in an amount considerably exceeding of the silicon chloride into silica, a corresponding amount of alumina being converted to aluminum chloride. Moreover, if an insufficient quantity of silicon chloride i. e., less than about 50 percent of the total weight, be admixed to the chlorine, formation of silicon chloride from the solid material containing silica and alumina takes place simultaneously with the conversion of art of the latter into alminum chloride. T us, by suitably adjusting the silicon chloride content in the gas mixture used for chlorination, the formation of SiCl, may be allowed to take place to the desired extent, or it may be entirely avoided, the chlorine being spent quantitativelyfor producing aluminum chloride.

In carrying out my invention in practice 1 preferably proceed as follows: A mixture of chlorine with silicon tetrachloride in a ratio as required bythe desired amount of SiCl, in the resulting products is brought into close contact with a mixture of a material containing both alumina and silica, and a substance containing carbon as areducing material, the substances being preferably nely ground, bri netted, and coked, for instance. as descri ed in .my copending application Ser. No. 200,499. The reaction takes place at about (DO-800 C. The va ors issuing from the reaction chamber aret en led awe and separated in known manner by cool them below the sublimation point of A10 but above the condensing o'nt of SiCl preferably to about 60 The silicon tetrachloride after separate condensation may then be reused in the process, or if produced in excess it may be disposed of in any other manner desired.

The charging of the chloride gas with the necessary amount of silicon tetrachloride may be effected in a very simple way in view of the fact that silicon chloride boils at 57 C. and has a high vapor tension even at ordinary temperature; therefore, by passing the chlorine gas through liquid silicon chloride the chlorine becomes saturated and the amount of silicon chloride, thus taken up by the chlorine, may be easily regulated by adjusting the temperature at which the saturation is carried out. Examples i 1. (Showing the 01d art): 100 kgs. of a mixture formed of clay and coke and lignite, coked at red heat and containing about percent Al O 55 percent SiO and 15 percent C, are treated with 102 kgs. of chlorine at about 700800 C. The resulting product consists of 71 kgs. A101 and 54 kgs. SiCl the residue being left amounting to about 336 kgs.

The chlorine is spent by forming both AlCl and SiCh.

2. (Showing the new process) 100 kgs. of the same startmg material as described in the foregoing example are treated with about 57 kgs. of chlorine to which about 60 kgs. of SiCl are admixed. Vapors containing 71 kgs. AlCl besides SiCl, are formed wherefrom after precipitating the AlCl about 60 kgs. SiCl are recovered by condensation, i. e. the same amount as was introduced. The residue of the raw material, thus treated, amounts'to about 65 kgs. The chlorine thus has been utilized for producing AlCl, ex-

clusively.

,3. 100 kgs. of the starting material used in Example 1 are treated with kgs. of chlorine at about 750 (1., 75 kgs. SiCl. being admixed to the chlorine. k AlCl are'formed and about 61.5 kgs. Si 1 are condensed, the residue amounting to about 70.5 kgs. This shows that 13.5 kgs. SiCl have reacted with A1 0 to form A101 i. e. a little more than 20 percent of the silicon chloride has reacted with the alumina instead of chlorine, according to the equation referred to above. From this it follows that the occasional admixture to the chlorine of an excessof SiCl, does no harm, this excess being utilized in favor of the formation of aluminum chloride.

' Claims:

. 1. The process for producing anhydrous aluminum chloride from raw materials con taining both alumina and silicic acid, which process comprises heating the said raw materials admixed with carbonaceous matter acting as reducing material in the presence of ch 0 rine, causing1 the material to react with chlorine charge with silicon tetrachloride vapors and separating the resulting aluprocess comprises adm said raw materials, briquetting the, mixture,

Lesa-731 silicon tetrachloride, contacting the condensate with chlorine gas and subjecting the resulting gaseous mixture to further reaction with said raw materials.

3. The process for producing anhydrous aluminum chloride from raw materials containing both alumina and silicic acid, which process comprises heating the said raw materials in the presence of carbon, causing the material to react with chlorine charged with silicon tetrachloride vapors, separating the aluminum chloride from the mixture of va-" pors by condensation, condensing the remaining silicon tetrachloride, contacting the condensate with chlorine gas and subjecting the resulting gaseous mixture to further reaction with said raw materials.

4. The process for producing anhydrous aluminum chloride from raw materials containing both alumina and silicic acid, which process comprises admixing carbonaceous matter with said raw materials, heating themixture to coke the carbonaceous matter, causing the material to react with chlorine charged with silicon tetrachloride vapors, separating the resulting aluminum chloride from the mixture of vapors by condensation, condensing the remaining silicon tetrachloride, contacting the condensate with chlorine gas and subjecting the resulting gaseous mixture to further reaction with said raw materials. 5. The process for producing anhydrous aluminum chloride from raw materials containing both alumina and silicic acid, which process comprises admixin carbonaceous matter to the said raw materials, heating the mixture to coke the carbonaceous matter, causing the mixture to react with chlorine charged with about an equal part by weight of silicon tetrachloride, se arating the resulting aluminum chloride rom the mixture of vapors by condensation, condensing the remaimng silicon tetrachloride, contacting the condensate with chlorine gas and subjecting the resulting gaseous mixture to further reaction with said raw materials.

6. The process for producing anh drous aluminum chloride from raw materi containing both alumina andsilicic acid, which ixing brown coal to the heating it to about 700? to 800 (3., cans the material to react with chlorine charg with about an equal part by weight of silicon tetrachloride, separating the resulting aluminum chloride from the mixture of vapors by condensation, admixing fresh chlorine with the remaining silicon tetrachloride and subjecting the resulting gaseous mixture to further reaction with said raw materials.

In testimony whereof I have hereunto set my hand. 4

KARL STAIB. 

